Project Summary/Abstract The mammalian brain builds and transforms representations of the outside world through the concerted activity of populations of neurons, but the extent to which spike times or spike counts are coordinated within these ensembles beyond pairs is not clear. Models of neural encoding predict variable frequencies of spike pattern occurrence, and models of decoding delineate requirements for spike time precision within the population response. While considerable effort has been made toward the development and refinement of the theoretical basis of such neural coding schemes, and predictions have been tested against single cell and pairwise data, there has been relatively little experimental data beyond pairs able to differentiate between competing hypotheses of population coding. The proposed career development plan aims to marry large-scale electrophysiology in primary visual cortex with analysis of specific predictions derived from computational and theoretical neuroscience work for spike time coordination beyond pairwise interactions. The candidate has a deep background in in vivo experimental techniques and proposes to receive training in the high-dimensional computational techniques and to use experimental data collected to validate specific theoretical predictions. This training will establish the skills necessary for a successful independent research career studying the mechanisms of information representation and transfer in visual cortex, bridging the gap between experimental and computational neuroscience. The candidate will carry out the mentored phase under the guidance of Dr. Clay Reid, a world expert in multiple aspects of mammalian central visual processing including anatomy, physiology, and computation. Additional advising from Dr. Eric Shea- Brown and Dr. Christof Koch will provide guidance in the theoretical and applied mathematical approaches required to implement and assess advanced models of neural encoding and decoding. The training will utilize the strengths of the Allen Institute for Brain Science in collecting large-scale data and the didactic opportunities at the University of Washington. In the independent phase the candidate will use the newly acquired analytical and modeling skills in combination with his previous training in optogenetic techniques to better constrain population measurements. This work will help establish a unique independent research program to elucidate the mechanisms underlying cortical representation.